refactor(tazjin/rlox): Introduce declarations in parser

Change-Id: I873fdd53319ec36da18926d9477e809a69dbace7
Reviewed-on: https://cl.tvl.fyi/c/depot/+/2288
Reviewed-by: tazjin <mail@tazj.in>
Tested-by: BuildkiteCI
This commit is contained in:
Vincent Ambo 2020-12-21 00:13:22 +01:00 committed by tazjin
parent 75ae25daa9
commit a104afa6ea
2 changed files with 37 additions and 16 deletions

View file

@ -1,5 +1,5 @@
use crate::errors::{report, Error, ErrorKind};
use crate::parser::{self, Expr, Literal, Program, Statement};
use crate::parser::{self, Declaration, Expr, Literal, Program, Statement};
use crate::scanner::{self, TokenKind};
// Run some Lox code and print it to stdout
@ -104,16 +104,24 @@ fn eval<'a>(expr: &Expr<'a>) -> Result<Literal, Error> {
}
}
fn run_program<'a>(program: &Program<'a>) -> Result<(), Error> {
for stmt in program {
match stmt {
Statement::Expr(expr) => {
eval(expr)?;
}
Statement::Print(expr) => {
let result = eval(expr)?;
println!("{:?}", result)
}
fn run_stmt<'a>(stmt: &Statement<'a>) -> Result<(), Error> {
match stmt {
Statement::Expr(expr) => {
eval(expr)?;
}
Statement::Print(expr) => {
let result = eval(expr)?;
println!("{:?}", result)
}
}
Ok(())
}
fn run_program<'a>(program: &Program<'a>) -> Result<(), Error> {
for decl in program {
match decl {
Declaration::Stmt(stmt) => run_stmt(stmt)?,
}
}

View file

@ -48,12 +48,20 @@ pub enum Statement<'a> {
Print(Expr<'a>),
}
pub type Program<'a> = Vec<Statement<'a>>;
#[derive(Debug)]
pub enum Declaration<'a> {
Stmt(Statement<'a>),
}
pub type Program<'a> = Vec<Declaration<'a>>;
// Parser
/*
program statement* EOF ;
program declaration* EOF ;
declaration varDecl
| statement ;
statement exprStmt
| printStmt ;
@ -79,10 +87,15 @@ struct Parser<'a> {
type ExprResult<'a> = Result<Expr<'a>, Error>;
type StmtResult<'a> = Result<Statement<'a>, Error>;
type DeclResult<'a> = Result<Declaration<'a>, Error>;
impl<'a> Parser<'a> {
// recursive-descent parser functions
fn declaration(&mut self) -> DeclResult<'a> {
Ok(Declaration::Stmt(self.statement()?))
}
fn statement(&mut self) -> StmtResult<'a> {
if self.match_token(&[TokenKind::Print]) {
self.print_statement()
@ -274,13 +287,13 @@ pub fn parse<'a>(tokens: Vec<Token<'a>>) -> Result<Program<'a>, Vec<Error>> {
let mut errors: Vec<Error> = vec![];
while !parser.is_at_end() {
match parser.statement() {
match parser.declaration() {
Err(err) => {
errors.push(err);
parser.synchronise();
}
Ok(stmt) => {
program.push(stmt);
Ok(decl) => {
program.push(decl);
}
}
}